Plant personnel often see the terms “sealed,” “waterproof,” and “dust tight” in marketing and technical literature for electrical equipment. In dusty or wet applications, such as industrial slurry manufacturing, offshore oil rigs, water/wastewater treatment facilities, and milling/hulling processes, the level of “sealedness” is of prime importance to avoid contamination. But what do these terms really mean and is there a way to precisely quantify that “sealedness?”
The answer is yes, according to Meredith Christman of IMI Sensors, a division of PCB Piezotronics (pcb.com, Depew, NY). In fact, an international standard that helps personnel do just that has been in place for almost 40 years.
In a recently posted white paper, Christman cites the International Electrotechnical Commission’s IEC Standard 60529: Degrees of Protection Provided by Enclosures that, in 1976, introduced the concept of quantifying a product’s level of “sealedness” with the establishment of the Ingress Protection (IP) Code. Limited to enclosures for electrical equipment with a rated voltage of less than or equal to 72.5 kV, this standard defines protection against ingress of body parts, solids, and liquids toward hazardous electrical or mechanical components.
Christman then goes on to explain how plant personnel can interpret the IP Code. Among other things, she includes details on:
In defining and quantifying the “sealedness” levels of the three ingress protection categories, i.e., “sealedness” against body parts, solids and liquids, the IEC Standard 60529 prescribes corresponding tests. General test requirements recommend the atmospheric conditions during which each test should take place, while specific test procedures stipulate the following:
• location of the contaminant source as compared to the electrical equipment
• length of time that the electrical equipment should be subjected to the contaminant
• amount of contaminant to which the electrical equipment should be subjected.
Specific IP ratings
Once a product has successfully passed the appropriate tests, it can be marketed with a specific IP rating. This rating consists of the IP designation followed by one of four alphanumeric characters, with each character identifying a particular level of protection or a specific nuance about a particular protection level.
Alphanumeric #1: Protection against ingress of body parts and solids (with priority to solids). Ratings range from no protection to protection against solids as fine as dust. When a product is rated to a particular level, it can be automatically assumed that that product could also be successfully rated to all other levels below it. Performing the tests associated with the lower levels of protection is not required.
Alphanumeric #2: Protection against ingress of liquids. Ratings range from no protection to protection against any liquid during a continuous-submersion application. When a product is rated to a particular splash level, it can be automatically assumed that that product could also be successfully rated to all other levels below it. However, when a product is rated to a particular submersion level, it can only be automatically assumed that the product could also be successfully rated to the other submersion levels below it without additional testing, but not to the lower splash levels. If a product needs to have both a splash and submersion rating, then both sets of applicable tests need to be performed.
Alphanumeric #3: Protection against ingress of body parts if not adequately described in alphanumeric #2.
Alphanumeric #4: Supplementary information.
For more details, download the white paper, “Keeping Out Contaminants: Understanding Ingress Protection Ratings” by clicking here and choosing the “Industrial” tab. MT
Meredith Christman is a product manager II with IMI Sensors, a division of PCB Piezotronics, Depew, NY, pcb.com.